Dynamo-electric machine.



W. HOLT DYNAMO ELECTRIC MACHINE.

APPLICATION FILED NOV. 3,1911.

Patented June 16, 1914.

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mun

I FYA gm: '57 gag K W. HOLT.

DYNAMO ELEG TRIC MACHINE.

APPLICATION FILED N013, 1911,

atented June 16, 1914.

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W. HOLT.

DYNAMO ELECTRIC MACHINE. APPLICATION FILED NOW-3,1911.

Patented June 16, 1914.

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iNVENTOR za z'zzz'amjio 22'- "UNITED snrs I To all I /I H1. it 7ll-ll l/ (JOINT/'11,

Be it. known that I, WILLIAM Hour, subject of the King of Great Britain, residing at 213 Slade road, Erdington, Birmingham, England, have invented certain new and useful Improvements in Dynamo-Electr c Machines, of which the following is a specificatio'n.

lhi"invention relates to dynamo-electric 10 machines,particularly of that class which are run at variable speeds, such as those employed in connection with electric lighting systems of railway trains, motor vehicles; and the like, where the generator 1s driven directly from the axle, and supplies the current in conjunction with accumulators. j

The; object of the present invention is to provide an improved and more eiiicient means for' rendering dynamo-electric machines substantially self-regulating and maintaining the current output practically constant over a wide variation of speed, or with a varying resistance connected across 25 the terminals.

A.ccording to this invention the dynamo comprises means for producing a cross magnetic field independent of the main field, andarmature brushes situated at the neutral positions of the armature which short-circuit armature coils under the influence of the cross field but outside the influence of the main-field, and wherein a current is generated, distinct with relation to the working current, which sets up a field in opposition to the main field, and exerts a demagnetizing eflt'ect on the main poles, so preventing the voltage from rising when the speed increases and maintaining a practically constant output. I

Figure 1 of the accompanying drawings represents diagrammatically a bl-polar machine embodying the" present invention, and shows the wiring connection when the ma- 5 chine is used in a train-Hg "3g or similar system. Fig. 2 is anothe diagrammatic view showing how certain'ot the armature conductors are short-circuited by the brushes. In this view the pole windings are omitted. .iEig. 3a'epresents' a modification in which the Rbrushes are divided. Fig. 4; illustrates a modification in which auxiliary windings in the faces of the main poles are used for producin the cross field. Fig. 5 represents a modi cation in which series windings are.

g :p'rovided on the auxiliary poles for produc- Specification of Letters Patent.

Application filed November 3, 1811.

duced by the armature windin directly by the current derived from DYNAMO-ELECTRIG Il IACHXNE.

Patented June 3th, Serial No. 655,411.

ing the desired regulation. Fig. 5 is view of another modification wherein the divided brushes are connected together throu demagnetizing winding on the inair oles. Fig. 7 illustrates how the salient auxiliary poles can be dispensed with and the of the frame used instead. Fig. 8 shows a further modification in which the number at auxiliary poles employed is only hi: the number of main poles.

Referring to Figs. 1 and 2, the inachi fundamentally of the bi-polar type, h two main poles a, Z), shunt wound (as shown or compound wound, in the usual manner. Disposed mid-way between these main poles, at right angles to their axis, are pair auxiliary poles c, d, which may either be unwound (as represented) so to he er:- cited solely by the cross'rnagnetization proor w and with a few series turns, so as to be excited we is arn'lature in addition to the saidwarniati. c excitation; or the said poles may be excited in any other suitable manner. The single nair of brushes, 0, e, of the armature 7" latter may be of any ordinary t pe situatedin the neutral position, r iatively to the main poles, and have asufficiently vzi bearing surface to make simultaneous tact with a plurality of adjacent-comma segments 9, so as t short-circuit cer. the armature coils which are least active, (shown in black section at j, Fig. its the armature revolves the current generated. in the active conductors j produces a crcs magnetic field having a direction righ angles to the main flux between the wound poles a, Z). This cross flux: traverses auxiliary poles c, d, and thereby e: them, the excitation being. further incr ts or decreased by the series or other wind" of the said poles, if such are employed. the short-circuited armature coils j n under the influence of the auxiliary poles,

ening the efiective field approzriniet eiy in 

